1. Fig. 1 Schematics and design of the device structure.
Schematics and design of the device structure. (A) Scanning electron microscopy picture of the phonon-polariton laser consisting of an active region based on 60 periods of the structure shown in (C) inside a double-metal cavity formed by the top and bottom contacts. (B) Phonon-polariton energy density along the growth direction (z). Most of the energy is concentrated in the barriers where the phonon part of the polariton is confined, while the photon part contributes with an approximately constant energy density. For the computed case with a phonon fraction of 0.5, each constituent makes up about half of the total polariton energy integrated over one period. (C) Band structure diagram of the phonon-polariton laser design (called EV2128), where the gain transition from the upper laser state (uls) to the lower laser state (lls) is indicated. The phonon and photon constituents, traveling in the plane of the laser, are schematically drawn. The color scale shows the electron density computed with a nonequilibrium Green’s function model at 100-K lattice temperature and shows an inverted population at the plotted bias (19 kV/cm).
Keita Ohtani et al. Sci Adv 2019;5:eaau1632
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